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Support for packed multidimensional arrays within packed structs

This commit is contained in:
Dag Lem 2022-12-03 19:54:47 +01:00
parent a64ed824ed
commit f94eec952f
2 changed files with 139 additions and 99 deletions
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178
frontends/ast/simplify.cc
View File

@ -273,9 +273,9 @@ static int range_width(AstNode *node, AstNode *rnode)
return rnode->range_left - rnode->range_right + 1;
}
[[noreturn]] static void struct_array_dimension_error(AstNode *node)
[[noreturn]] static void struct_array_packing_error(AstNode *node)
{
log_file_error(node->filename, node->location.first_line, "Currently limited to two dimensions in packed struct/union member %s\n", node->str.c_str());
log_file_error(node->filename, node->location.first_line, "Unpacked array in packed struct/union member %s\n", node->str.c_str());
}
static void save_struct_array_width(AstNode *node, int width)
@ -291,15 +291,6 @@ static void save_struct_range_swapped(AstNode *node, bool range_swapped)
}
static int get_struct_array_width(AstNode *node)
{
// This function is only useful for up to two array dimensions.
log_assert(node->multirange_dimensions.size() <= 2);
// the stride for the array, 1 if not an array
return (node->multirange_dimensions.size() != 2 ? 1 : node->multirange_dimensions[1]);
}
static int size_packed_struct(AstNode *snode, int base_offset)
{
// Struct members will be laid out in the structure contiguously from left to right.
@ -341,11 +332,12 @@ static int size_packed_struct(AstNode *snode, int base_offset)
width *= array_count;
}
else {
// Currently limited to at most two dimensions.
struct_array_dimension_error(node);
// The Yosys extension for unpacked arrays in packed structs / unions
// only supports memories, i.e. e.g. logic [7:0] a [256] - see above.
struct_array_packing_error(node);
}
} else {
// Vector.
// Vector
save_struct_array_width(node, width);
save_struct_range_swapped(node, node->children[0]->range_swapped);
}
@ -355,19 +347,19 @@ static int size_packed_struct(AstNode *snode, int base_offset)
node->children.clear();
}
else if (node->children.size() > 0 && node->children[0]->type == AST_MULTIRANGE) {
// packed 2D array, e.g. bit [3:0][63:0] a
auto rnode = node->children[0];
if (node->children.size() != 1 || rnode->children.size() != 2) {
// Currently limited to at most two dimensions.
struct_array_dimension_error(node);
// Packed array, e.g. bit [3:0][63:0] a
if (node->children.size() != 1) {
// The Yosys extension for unpacked arrays in packed structs / unions
// only supports memories, i.e. e.g. logic [7:0] a [256] - see above.
struct_array_packing_error(node);
}
width = 1;
for (auto rnode : node->children[0]->children) {
int rwidth = range_width(node, rnode);
save_struct_array_width(node, rwidth);
save_struct_range_swapped(node, rnode->range_swapped);
width *= rwidth;
}
int array_count = range_width(node, rnode->children[0]);
save_struct_array_width(node, array_count);
save_struct_range_swapped(node, rnode->children[0]->range_swapped);
width = range_width(node, rnode->children[1]);
save_struct_array_width(node, width);
save_struct_range_swapped(node, rnode->children[1]->range_swapped);
width *= array_count;
// range nodes are now redundant
for (AstNode *child : node->children)
delete child;
@ -426,75 +418,53 @@ static AstNode *multiply_by_const(AstNode *expr_node, int stride)
return new AstNode(AST_MUL, expr_node, node_int(stride));
}
static AstNode *offset_indexed_range(int offset, int stride, AstNode *left_expr, AstNode *right_expr)
static void normalize_struct_index(AstNode *rnode, AstNode *member_node, int dimension)
{
// adjust the range expressions to add an offset into the struct
// and maybe index using an array stride
auto left = left_expr->clone();
auto right = right_expr->clone();
if (stride > 1) {
// newleft = (left + 1) * stride - 1
left = new AstNode(AST_SUB, multiply_by_const(new AstNode(AST_ADD, left, node_int(1)), stride), node_int(1));
// newright = right * stride
right = multiply_by_const(right, stride);
}
// add the offset
if (offset) {
left = new AstNode(AST_ADD, node_int(offset), left);
right = new AstNode(AST_ADD, node_int(offset), right);
}
return new AstNode(AST_RANGE, left, right);
}
static AstNode *make_struct_index_range(AstNode *node, AstNode *rnode, int stride, int offset, AstNode *member_node)
{
// This function should be rewritten to support more than two array dimensions.
log_assert(member_node->multirange_dimensions.size() <= 2 && member_node->multirange_swapped.size() <= 2);
if (member_node->multirange_swapped[0]) {
// The struct item has swapped range; swap index into the struct accordingly.
int msb = member_node->multirange_dimensions[0] - 1;
if (member_node->multirange_swapped[dimension]) {
// The dimension has swapped range; swap index into the struct accordingly.
int msb = member_node->multirange_dimensions[dimension] - 1;
for (auto &expr : rnode->children) {
expr = new AstNode(AST_SUB, node_int(msb), expr);
}
}
// generate a range node to perform either bit or array indexing
if (rnode->children.size() == 1) {
// index e.g. s.a[i]
return offset_indexed_range(offset, stride, rnode->children[0], rnode->children[0]);
}
else if (rnode->children.size() == 2) {
// slice e.g. s.a[i:j]
return offset_indexed_range(offset, stride, rnode->children[0], rnode->children[1]);
}
else {
struct_op_error(node);
}
}
static AstNode *slice_range(AstNode *rnode, AstNode *snode, AstNode *member_node)
static AstNode *struct_index_lsb_offset(AstNode *lsb_offset, AstNode *rnode, AstNode *member_node, int dimension, int &stride)
{
// This function should be rewritten to support more than two array dimensions.
log_assert(member_node->multirange_dimensions.size() <= 2 && member_node->multirange_swapped.size() <= 2);
if (member_node->multirange_swapped[1]) {
// The second dimension has swapped range; swap index into the struct accordingly.
int msb = member_node->multirange_dimensions[1] - 1;
for (auto &expr : snode->children) {
expr = new AstNode(AST_SUB, node_int(msb), expr);
normalize_struct_index(rnode, member_node, dimension);
stride /= member_node->multirange_dimensions[dimension];
auto right = rnode->children.back()->clone();
auto offset = stride > 1 ? multiply_by_const(right, stride) : right;
return new AstNode(AST_ADD, lsb_offset, offset);
}
static AstNode *struct_index_msb_offset(AstNode *lsb_offset, AstNode *rnode, int stride)
{
log_assert(rnode->children.size() <= 2);
// Offset to add to LSB
AstNode *offset;
if (rnode->children.size() == 1) {
// Index, e.g. s.a[i]
offset = node_int(stride - 1);
}
else {
// rnode->children.size() == 2
// Slice, e.g. s.a[i:j]
auto left = rnode->children[0]->clone();
auto right = rnode->children[1]->clone();
auto slice_offset = new AstNode(AST_SUB, left, right);
if (stride == 1) {
offset = slice_offset;
}
else {
// offset = (msb - lsb + 1)*stride - 1
auto slice_width = new AstNode(AST_ADD, slice_offset, node_int(1));
offset = new AstNode(AST_SUB, multiply_by_const(slice_width, stride), node_int(1));
}
}
// apply the bit slice indicated by snode to the range rnode
log_assert(rnode->type==AST_RANGE);
auto left = rnode->children[0];
auto right = rnode->children[1];
log_assert(snode->type==AST_RANGE);
auto slice_left = snode->children[0];
auto slice_right = snode->children[1];
auto width = new AstNode(AST_SUB, slice_left->clone(), slice_right->clone());
right = new AstNode(AST_ADD, right->clone(), slice_right->clone());
left = new AstNode(AST_ADD, right->clone(), width);
return new AstNode(AST_RANGE, left, right);
return new AstNode(AST_ADD, lsb_offset, offset);
}
@ -509,26 +479,36 @@ AstNode *AST::make_struct_member_range(AstNode *node, AstNode *member_node)
// no range operations apply, return the whole width
return make_range(range_left, range_right);
}
// This function should be rewritten to support more than two array dimensions.
log_assert(member_node->multirange_dimensions.size() <= 2 && member_node->multirange_swapped.size() <= 2);
int stride = get_struct_array_width(member_node);
if (node->children.size() == 1 && node->children[0]->type == AST_RANGE) {
// bit or array indexing e.g. s.a[2] or s.a[1:0]
return make_struct_index_range(node, node->children[0], stride, range_right, member_node);
if (node->children.size() != 1) {
struct_op_error(node);
}
else if (node->children.size() == 1 && node->children[0]->type == AST_MULTIRANGE) {
// multirange, i.e. bit slice after array index, e.g. s.a[i][p:q]
log_assert(stride > 1);
auto mrnode = node->children[0];
auto element_range = make_struct_index_range(node, mrnode->children[0], stride, range_right, member_node);
// then apply bit slice range
auto range = slice_range(element_range, mrnode->children[1], member_node);
delete element_range;
return range;
// Range operations
auto rnode = node->children[0];
auto lsb_offset = node_int(member_node->range_right);
int stride = range_left - range_right + 1;
// Calculate LSB offset for the final index / slice
if (rnode->type == AST_RANGE) {
lsb_offset = struct_index_lsb_offset(lsb_offset, rnode, member_node, 0, stride);
}
else if (rnode->type == AST_MULTIRANGE) {
// Add offset for each dimension
auto mrnode = rnode;
for (size_t i = 0; i < mrnode->children.size(); i++) {
rnode = mrnode->children[i];
lsb_offset = struct_index_lsb_offset(lsb_offset, rnode, member_node, i, stride);
}
}
else {
struct_op_error(node);
}
// Calculate MSB offset for the final index / slice
auto msb_offset = struct_index_msb_offset(lsb_offset->clone(), rnode, stride);
return new AstNode(AST_RANGE, msb_offset, lsb_offset);
}
static void add_members_to_scope(AstNode *snode, std::string name)

60
tests/svtypes/struct_array.sv
View File

@ -81,6 +81,66 @@ module top;
always_comb assert(s3_b==80'hFC00_4200_0012_3400_FFFC);
struct packed {
bit [0:7] [0:1] [0:3] a;
bit [0:15] b; // filler for non-zero offset
} s3_lll;
initial begin
s3_lll = '0;
s3_lll.a[5:6] = 16'h1234;
s3_lll.a[2] = 8'h42;
s3_lll.a[0] = '1;
s3_lll.a[0][1][2:3] = '0;
s3_lll.b = '1;
s3_lll.b[14:15] = '0;
end
always_comb assert(s3_lll==80'hFC00_4200_0012_3400_FFFC);
struct packed {
bit [0:7] [1:0] [0:3] a;
bit [0:15] b; // filler for non-zero offset
} s3_lbl;
initial begin
s3_lbl = '0;
s3_lbl.a[5:6] = 16'h1234;
s3_lbl.a[2] = 8'h42;
s3_lbl.a[0] = '1;
s3_lbl.a[0][0][2:3] = '0;
s3_lbl.b = '1;
s3_lbl.b[14:15] = '0;
end
always_comb assert(s3_lbl==80'hFC00_4200_0012_3400_FFFC);
struct packed {
bit [0:7] [0:1] [3:0] a;
bit [0:15] b; // filler for non-zero offset
} s3_llb;
initial begin
s3_llb = '0;
s3_llb.a[5:6] = 16'h1234;
s3_llb.a[2] = 8'h42;
s3_llb.a[0] = '1;
s3_llb.a[0][1][1:0] = '0;
s3_llb.b = '1;
s3_llb.b[14:15] = '0;
end
always_comb assert(s3_llb==80'hFC00_4200_0012_3400_FFFC);
`ifndef VERIFIC
// Note that the tests below for unpacked arrays in structs rely on the
// fact that they are actually packed in Yosys.